Temperature dependence of the first-order metal-insulator transition in VO_2 and programmable critical temperature sensor

摘要

For VO_2-based two-terminal devices, the first-order metal-insulator transition (MIT, jump) is controlled by an applied voltage and temperature, and an intermediate monoclinic metal phase between the MIT and the structural phase transition (SPT) is observed. The conductivity of this phase linearly increases with increasing temperature up to T_(SPT) ≈ 68℃ and becomes maximum at T_(SPT). Optical microscopic observation reveals the absence of a local current path in the metal phase. The current uniformly flows throughout the surface of the VO_2 film when the MIT occurs. This device can be used as a programmable critical temperature sensor where the applied voltage is controlled by a program.